In multistage rotary machines used for energy conversion for example, a fluid is used to produce rotational motion. In a gas turbine engine, for example, a gas is compressed in a compressor and mixed with a fuel source in a combustor. The combination of gas and fuel is then ignited to create a combustion gas that defines a working gas that is directed to turbine stage(s) to produce rotational motion. Both the turbine stage(s) and the compressor have stationary or non-rotary components, such as vanes, for example, that cooperate with rotatable components, such as rotor blade structures, for example, for compressing and expanding the operational gases. Many components within the machines must be cooled by cooling air to prevent the components from overheating.
Leakage of a working gas from a hot gas path to a disc cavity in the machines reduces performance and efficiency. Working gas leakage into the disc cavities yields higher disc and blade root temperatures and may result in reduced performance and reduced service life and/or failure of the components in and around the disc cavities.